source/libmarklin/simplephysics.cpp

   1 /* $Id$
   2
   3 This file is part of the MSP Märklin suite
   4 Copyright © 2010  Mikkosoft Productions, Mikko Rasa
   5 Distributed under the GPL
   6 */
   7
   8 #include <msp/core/except.h>
   9 #include <msp/time/units.h>
  10 #include "simplephysics.h"
  11
  12 using namespace std;
  13 using namespace Msp;
  14
  15 namespace Marklin {
  16
  17 SimplePhysics::SimplePhysics():
  18         target_speed(TrainControl::continuous("speed", -1000, 1000)),
  19         accel(0.07),
  20         speed(0)
  21 {
  22         target_speed.set(0);
  23 }
  24
  25 void SimplePhysics::set_control(const string &name, float v)
  26 {
  27         if(name=="speed")
  28                 target_speed.set(v);
  29 }
  30
  31 const TrainControl &SimplePhysics::get_control(const string &name) const
  32 {
  33         if(name=="speed")
  34                 return target_speed;
  35         else
  36                 throw KeyError("Unknown control", name);
  37 }
  38
  39 float SimplePhysics::get_braking_distance() const
  40 {
  41         return speed*speed/(2*accel);
  42 }
  43
  44 void SimplePhysics::tick(const Time::TimeDelta &dt)
  45 {
  46         float secs = dt/Time::sec;
  47         if(speed<target_speed.value)
  48         {
  49                 speed += secs*accel;
  50                 if(speed>target_speed.value)
  51                         speed = target_speed.value;
  52         }
  53         else if(speed>target_speed.value)
  54         {
  55                 speed -= secs*accel;
  56                 if(speed<target_speed.value)
  57                         speed = target_speed.value;
  58         }
  59 }
  60
  61 } // namespace Marklin